Chapter 18
Section 1 Introduction to Ecology
Chapter 18
Section 1 Introduction to Ecology
Objectives
Interdependence: A Key Theme in Ecology
• Identify a key theme in ecology.
• Organisms and Their Environments
– Species interact with both other species and their
nonliving environment.
– Interdependence is a theme in ecology—one
change can affect all species in an ecosystem.
• Describe an example showing the effects of
interdependence upon organisms in their
environment.
• Identify the importance of models to ecology.
• State the five different levels of organization at which
ecology can be studied.
Chapter 18
Section 1 Introduction to Ecology
Ecological Models
Chapter 18
Section 1 Introduction to Ecology
Making an
Ecosystem Model
• Ecological models help to explain the environment.
Chapter 18
Section 1 Introduction to Ecology
Levels of Organization
• Ecologists recognize a hierarchy of organization in
the environment: biosphere, ecosystem, community,
population, and organism.
Chapter 18
Section 1 Introduction to Ecology
Levels of Organization
Chapter 18
Section 1 Introduction to Ecology
Chapter 18
Section 1 Introduction to Ecology
Levels of Organization, continued
Levels of Organization, continued
• The Biosphere
– The broadest, most inclusive level of organization
is the biosphere, the volume of Earth and its
atmosphere that supports life.
• Ecosystems
– The biosphere is composed of smaller units called
ecosystems.
– An ecosystem includes all of the organisms and
the nonliving environment found in a particular
place.
Chapter 18
Section 1 Introduction to Ecology
Chapter 18
Section 2 Ecology of Organisms
Levels of Organization, continued
Objectives
• Communities, Populations, and Organisms
– A community is all the interacting organisms
living in an area.
– Below the community level of organization is the
population level, where the focus is on the
individual organisms of a single species.
• Compare abiotic factors with biotic factors, and list
two examples of each.
• Describe two mechanisms that allow organisms to
survive in a changing environment.
• Explain the concept of the niche.
Chapter 18
Section 2 Ecology of Organisms
Ecosystem Components
• Biotic and Abiotic Factors
– Both biotic, or living, factors and abiotic, or
nonliving, factors influence organisms. Examples
of abiotic factors are climate, sunlight, and pH.
Chapter 18
Section 2 Ecology of Organisms
Comparing Biotic and Abiotic Factors
Click below to watch the Visual Concept.
Visual Concept
Chapter 18
Section 2 Ecology of Organisms
Chapter 18
Section 2 Ecology of Organisms
Organisms in a Changing Environment
Organisms in a Changing Environment,
continued
• Acclimation
– Some organisms can adjust their tolerance to
abiotic factors through the process of acclimation.
• Control of Internal Conditions
– Conformers are organisms that do not regulate
their internal conditions; they change as their
external environment changes.
– Regulators use energy to control some of their
internal conditions.
Chapter 18
Section 2 Ecology of Organisms
Organisms in a Changing Environment,
continued
• Escape from Unsuitable Conditions
– Some species survive unfavorable environmental
conditions by becoming dormant or by migrating.
Chapter 18
Chapter 18
The Niche
• A niche is a way of life, or a role in an ecosystem.
Section 3 Energy Transfer
Objectives
Vocab
• Summarize the role of producers in an ecosystem.
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• Identify several kinds of consumers in an ecosystem.
• Explain the important role of decomposers in an ecosystem.
• Compare the concept of a food chain with that of a food web.
• Explain why ecosystems usually contain only a few trophic
levels.
Section 2 Ecology of Organisms
ProducersConsumersHerbivoresCarnivoresOmnivoresDecomposersHeterotrophsAutotrophs-
Chapter 18
Section 3 Energy Transfer
Chapter 18
Section 3 Energy Transfer
Producers
Consumers
• Most producers are photosynthetic and make
carbohydrates by using energy from the sun.
• Consumers obtain energy by eating other organisms
and include herbivores, omnivores, carnivores,
detritivores, and decomposers.
Chapter 18
Section 3 Energy Transfer
The energy pyramid
Energy Flow
• Producers-create their own energy (plants)
• Consumers-have to eat for energy (animals)
• Food Chains and Food Webs
– A single pathway of energy transfer is a food
chain.
– A network showing all paths of energy transfer is a
food web.
Chapter 18
Section 3 Energy Transfer
Food Chain in an Antarctic Ecosystem
Chapter 18
Food Web
in an
Antarctic
Ecosystem
Section 3 Energy Transfer
Chapter 18
Section 3 Energy Transfer
Chapter 18
Section 4 Ecosystem Recycling
Energy Flow, continued
Objectives
• Energy Transfer
– Ecosystems contain only a few trophic levels
because there is a low rate of energy transfer
between each level.
• List four major biogeochemical cycles.
• Summarize three important processes in the water cycle.
• Outline the major steps in the carbon cycle.
• Describe the role of decomposers in the nitrogen cycle.
• Summarize the major steps of the phosphorus cycle.
Chapter 18
Section 4 Ecosystem Recycling
The Water Cycle
Chapter 18
Section 4 Ecosystem Recycling
Water Cycle
• Key processes in the water cycle are evaporation,
transpiration, and precipitation.
Chapter 18
Section 4 Ecosystem Recycling
The Carbon Cycle
• Photosynthesis and cellular respiration are the two
main steps in the carbon cycle.
Chapter 18
Carbon Cycle
Section 4 Ecosystem Recycling
Chapter 18
Section 4 Ecosystem Recycling
Nitrogen Cycle
Nitrogen Cycle
• Nitrogen-fixing bacteria are important in the
nitrogen cycle because they change nitrogen gas
into a usable form of nitrogen for plants.
Chapter 18
Chapter 18
Section 4 Ecosystem Recycling
Phosphorus Cycle
• In the phosphorus cycle, phosphorus moves from
phosphate deposited in rock, to the soil, to living
organisms, and finally to the ocean.
Section 4 Ecosystem Recycling